The Low-Down on Double-Dig Gardens

I hear and read many people who are completely against double-digging, and to state this upfront, for those most part, I’m in complete agreement with their assessment. I am a believer in no-dig gardens. Even more so, I think being patient with our soil situations—planting what will grow and piling organic matter atop the soil to replenish the nutrient cycle—works. I’ve seen it work in dry situations, in clay situations, in sandy situations.

In a word, I know that, with a little time and some simple measures, we can reinvigorate the planet, at least the little patches we have some say over. I mention this to establish that I’ve come to double-dig gardens with this mindset: the answers to our fertility woes are not dominating nature but rather collaborating with it. Nature is constantly working to repair its soil problems and stabilize the eco-system, so we don’t need to fight it but simply better enable it.

However, it is worth noting that some of our garden beds, even in a permaculture system, are not exactly the way nature would do it. Kitchen gardens are intensively managed areas in which we often ask more of the soil than natural systems would. Few of us are living primarily off of perennial crops, so we must accept that annuals will feature somewhere, to some degree, in our self-sustaining cultivation plans. That will likely mean amending soil in organic, yes, but still unnatural ways.

The Issues with Double-Digging

Video: How to Make a No-Dig Garden

Double-digging has several things that people object to. That begins, of course, with digging at all. It’s becoming more and more widely accepted that digging and/or tilling in the garden is not a long-term plan for food production. Digging destroys the soil life, which at first works to the gardener’s advantage as the corpses and such decompose, but the ultimate outcome is that, with no soil life remaining, all of the benefits those organisms naturally provide—aeration, fertilization, decomposition, etc.—are increasingly missing.

Another topic commonly brought up with double-digging, as with tilling, is that it mixes subsoil with topsoil, creating a less nutrient-rich growing medium. Root systems, in principle, are meant to work with the natural layering of soil, where leaf litter covers humus atop soil that has buried the subsoil. The shallow thin roots spread outwards to collect as much nutrients as possible, while fewer, thicker, deeper roots mine minerals from the subsoil. Mixing this all up isn’t in tune with how roots actually function.

There are more considerations. When we dig, we loosen soil, and loose soil sinks ecosystems because it is much more susceptible to erosion by wind and water. When we dig we unearth seeds that have been waiting for a chance to become weeds, while these weeds, left alone, would slowly rebuild the soil and system, they usually aren’t our goal in creating garden beds. When we dig, we release carbon into the atmosphere, while our planetary goal should be more geared towards sequestering it in plant life.

All of this and it’s extremely labor-intensive.

In Bed with Double-Dig Devil’s Advocate

Video: Double Digging

Not entirely to flip-flop, but a carefully constructed double-dig bed does address some of the claims brought against it. Done well, soil layers remain or are recreated as they should be: subsoil, soil, humus, and organic litter. Done well, the risk of erosion is dramatically decreased, and the topsoil—presumably depleted—is revived with nutrients, even life. Done well, weeds are suppressed, and drainage or water absorbtion is increased. The method doesn’t necessarily equate to complete destruction.

Sometimes, one might say, double-dig beds are useful. When soil is completely compacted, void of plants, and lacking in fertility; when the space is near the house and to be heavily managed by humans anyway for intensive food production, zone one food production; could double-dig beds not be a viable method? Certainly, it’s not the only method, but must we demonize it so? Can we not imagine it as something that might actually function well and sustainably in the right hands?

• If we take only the topsoil out, not mixing soil layers, and aerate the subsoil with a fork, never turning it, have we not maintained some soil life while instantaneously aerating and possible amending the—presumably depleted—topsoil, including inoculating it with new soil life to account any destroyed by digging.

• Wouldn’t this quickly deal with compaction issues in areas—Zone 1—where we are meant to first begin cultivation, and doing so in abundance, allowing us to then concentrate on building our long-term sustainable system atop something that can produce now rather than in six months?

• If we then, cover our double-dig beds—as we should—with a layer of humus or humus-like compost, mulching over that with organic litter, have we not in fact rebuilt the soil layers as they would ideally be, only with drainage, erosion, and aeration issues more immediately addressed?

• In the case of labor, might we also say that, in some circumstance, small gardens in largely urban areas, gathering the materials required to sheet mulch or utilize other no-dig methods, which are resource-intensive, could require more work than double-digging and using less organic material for the top two layers only?

A Singular Double-Dig Method

Video: No-Rules Compost

Truth be known, double-digging beds has not been something I’ve often utilized or something I often see as the best option, but I also think—in permaculture—we are to examine and analyze methods for what they are: tools we can utilize. We don’t have to use the same technique every time in every situation. In fact, permaculture teaches us not to do so, that our job is to find the right solution for each individual set of circumstances. With that in mind, it seems a bit pious (in the devoted no-dig sense) to claim double-digging should never be a viable option.

I like to think that, by and large, while many certainly wouldn’t adopt the technique, the overall objection to double-dig beds is to the notion of repeating the process again and again, a la annually tilling a garden. In this case, I would have to agree that double-digging does have a destructive, unsustainable element to it. However, if we are digging then fostering the soil life to blossom, afterwards feeding it undisturbed from the top with leaf litter from perennial plants, as naturally happens, in this case, have we really done something so different than digging a swale or building a sheet-mulch bed on hardpan?

The wider issue here, for me, is that sometimes I feel certain techniques and terminology come with a fingers-in-the-ears approach from their practitioners, such as with composting, and on the whole, that warrants a little worry. Some would suggest double-digging as a worthwhile consideration in certain instances. That’s not to say the buck stops here, but experienced voices—even of those not doing things exactly as we might—are worthy of paying attention to. And, in much the same way, double-digging seems an instrument that sometimes strikes the right note.

While I know the damning comments are likely to follow below, regardless, I’d again like to remind that this was not an argument that all gardeners in all places should use double-digging all the time but rather recognition that there may be a place for it for some gardeners at some time.

14 thoughts on “The Low-Down on Double-Dig Gardens”

It’s important to remember that good permaculture design considers energy efficiency. If your soil is compacted, it may be worthwhile digging it ONCE, if soil is depleted to ridiculous levels, you may kick-start the process with a synthetic fertilizer, but what needs to be considered is the long term benefit gained for the energy expended.

With regular garden beds, the soil shouldn’t be compacted if we design then properly so that they’re an ergonomic width that provides adequate reach so we don’t need to step in our garden beds, or we have proper paths within the garden. Using mulch will prevent compaction of the soil surface caused by rain, and earthworms will keep the soil well dug :)

Pull and drop weeds….. I have tried this many times… ONLY to find that the weeds seem to re grows in masses… I have read the same in Holzer’s books… but it does not seem to work for me.. NOW I am pulling and soaking in a large rubbish bin, to make weed tea / fertilizer… I have given up on pulling and dropping… don’t know what I am doing wrong it experts seem to have success???

Well I’m not really an expert, maybe it depends on the plant you’re pulling? Some will reproduce via parts left in the ground. Because of that old tale about dandelions regrowing from a piece of taproot I’m paranoid enough to chop the root off the dandy and throw it in the compost pile while leaving its leaves on the ground. I don’t know if it could get comfy and start growing again if pulled and laid down sideways but I still do it. And of course a good layer of mulch helps.

Just a note that articles like this help me weigh the decision to move away from tillage thinking. I developed some expertise in tillage-based gardening and need to build my knowledge to move away from that mindset with success.

I have two Biointnesive certs from John Jeavons and two Permaculture certs from Geoff Lawton and another person. When setting up a vegetable garden initially, double digging done correctly is both useful and beneficial to what you are trying to achieve. Correct double digging moves the soil over by the width of one trench, say one foot. Now, it is almost impossible to retain the existing soil layers exactly, but you are definitely not turning the soil. The use of double digging amongst other things is to decompact soil quickly allowing roots to go downwards and not sideways, in turn allowing for more intensiive planting. It loosens soil to a depth of two feet, allowing for a deeper penetration of essentials, such as oxygen, to microorganism. Contrary to the Biointensive method, I would double dig a bed more than once unless the ground was so compacted the first year that another round the next year would allow you to loosen the soil to two feet. It is very useful to take elements of different methods depending on your circumstances. With no judgement, any hint of fanaticism towards one method will only stifle your freedom to be intelligently flexible. Much of gardening is in seeing what happens. Double dig one bed and not the one right beside it. See what happens.

When we first started gardening on our 10-15 degree west to east incline we quickly learned to orient the beds across rather than up and down the bank. The rains of our southeastern U.S. home can come as 3 day deluges of 2 to 5 inches between 3 week to 3 month droughts. This turned our original east-west oriented beds into water slides. We also found hard red clay within a foot of the top of our stiff red soil. So we started double digging. What we dug were similar to hugelkultur topped with lasagne gardening, excluding manure and including layers of soil — all buried. And we added down slope edging or logs to discourage runoff. The paths have never been dug. Our beds have not been tilled except to occasionally stir in top layer amendments since we dug them 4 years ago, and they’re full of mycorrhizal fungi, bugs and worms. We are over 60 and really did not want to wait the 20 years some say top dressing or up bank swales might take to fully repair our soil.

Before I adopted a Synergistic approach, I double-dug my garden beds. This was primarily to remove the plentiful, very large river rocks and amend the coarse, sandy soil with organic matter. It was a zone 1 “kitchen” garden. I also created raised beds and added a well-recommended garden soil blend from a local soil and gravel center. I mulched the beds with straw and had a very successful first season.

BUT, the following year was not as successful. I didn’t re-double-dig. The slugs found the straw a wonderful habitat. I imagine, in hindsight, that I did have some settling of the soil. But really I just didn’t give it the attention (energy and nutrient input) it needed, having burned through that initial burst of nutrient release. The plants after that never seemed to do as well.

Since then I have adopted, and heartily endorse Emilia Hazelip’s Synergistic Approach. Dig once to establish the shape and form of the beds, then never again. Mulch the beds, keep the roots in the ground and never step in the beds. In my current garden I am not even digging the beds/paths but that’s for reasons beyond the scope of this article and comment.

i agree there are times when digging and looosening compaction is necessary, but usually only once, after which it is important to keep from compacting the soil again and to cover with plenty of mulch so as to keep moisture and soil life in the newly dug area. I put a couple of stepping stones in the bed if I need to access these areas. That prevents compaction re-occurring especially in heavy clay soils.

I’m glad someone has the balls to stand up and say not one system fits all and recognize the problem for what it is. I think a part of permaculture IS to think out of the square.
I agree there are times to alter methods as long as it has been well thought out and in line with permaculture principles.
I have almost pure sand where i want to farm. I have used double dig method successfully because there was very little life to start with. Now i can build on this to increase soil and the life contained in it.

I double dug a large portion of my parent’s back yard to alleviate compaction and introduce lime, organic fertilizer in small doses to the bottom layer.

The beds were laid out with pathways, keyholes, wheelbarrow turnarounds, etc. The beds were immediately covered with leaf compost and a layer of wood chip on top of that. Then transplanted fairly intensely with annual veg and many herbs for spring-summer, then cover cropped in the fall. The garden produced quite well. The whole thing is documented here on permaculture news if you search for Nottinghill Forest Garden.

Previously the clay was so compacted you could barely get a shovel in it. Now, 5 years later, it’s a minimal disturbance young forest garden with two ponds and improving soil.

Double digging has its place. I don’t tend to listen much to people who have 100% pro or con positions. Absolute positions are inflexible and insular, IMO.

I’ve tried piling organic matter atop a compacted clay, with the idea that it would bring life and regenerate it. It did not work, for a very simple reason: air. When a soil lacks air, it cannot digest the organic matter you provide to it, so the compacted soil below and organic matter above evoute separately, until generating a mire if we keep piling organic matter. Air is fundamental, and double-digging is a valuable tool to provide it. If it is done correctly, it can be done once and you can then grow food without digging for years. Double-digging is the best way to create a no-dig garden.